Glycol chiller maintenanceis of special importance to maintain the quantity and quality of the chilled water that is supplied and to avoid inconveniences with freezing of the fluid, deterioration of facilities, and heat exchange problems.
Ethylene glycol:
Ethylene glycol is an efficient and generally less expensive antifreeze protectant than propylene, but it is toxic and therefore facilities must adhere to proper safety protocols when applying or discharging it.
Propylene glycol
This is a non-toxic alternative to ethylene glycol, but it is also more expensive. For facilities that process food or those with green or organic initiatives, this is the obvious choice.
Aspects of Glycol Maintenance in Chillers:
- Checking for good glycol pressure is one way to verify that the pump is working and that the chiller is delivering the normal amount of glycol.
- An extreme drop in pressure could mean there is a problem with your process piping or a low glycol level in your reservoir.
- Checking the glycol level in your reservoir is easy to do as there is an external sight tube.
- Low glycol levels can cause major difficulties throughout the cooler.
- Checking the glycol mix is done with a refractometer.
- Keeping the glycol at a 26.5 Brix mix is a must in your cooler. That results in 35% propylene glycol to 65% water.
- Test the freezing point of the mixture.
- Adjust or replace mix as needed. Typically, the range is 20-25% glycol; however, each manufacturer is different, so check their recommendations before making any changes.
- If the glycol levels are too low, or the glycol in your system breaks down, you may be in for some expensive difficulties.
- Calculate the lowest temperature your system can be subjected to, to determine the desired freezing point. Then refer to the freezing point table (for example, the one above) to find the desired concentration.
- Ideally, the pH should be between 8 and 10. If your pH is too low, you may need to add additional inhibitors or flush and refill the system, depending on your lab results.
- Measurement of the alkalinity reserve will help determine whether the liquid can be restored. If the reserve alkalinity is depleted, the useful life of the fluid has expired and the system will need to be flushed and refilled.
- Automotive antifreeze should never be used because it is formulated to cool the engine and can cause difficulties with flow rates with pressures, and reduced heat transfer.
- Uninhibited glycol and water mixtures are highly corrosive. Inhibitors protect against corrosion, scale, and rust and act as pH buffers and biocides.
- Never use less than 25% glycol, this will ensure that an adequate amount of inhibitors is present. Never over mix – use only the concentration of glycol needed to protect equipment.
- DO NOT mix different types of glycol or different brands. Incompatibilities can lead to formulation separation, plugging filters, strainers, and pump suctions, as well as reducing its transfer properties.
- Check local regulations for measures regarding glycol and antifreeze solutions. Soil structure, water table, drainage, and disposal may be things to consider.
- A glycol solution is denser than water and does not offer the same level of heat transfer as water. Therefore, it will produce slightly reduced cooling capacity, exclude pumping power consumption, and highlight fluid temperature differences.
- Most systems use running water from the “tap”. However, the proper application of inhibitors is vitally important to prevent damage to the cooling system.
- Using distilled, demineralized, deionized, or RO water will eliminate all the unpredictability associated with public mains water.
- The chilled water system must be flushed, cleaned, and sanitized before adding a new water-glycol solution.
- The water and glycol solution should be sampled and analyzed periodically to ensure that no problem arises.
